Letter | Published:

The close environments of accreting massive black holes are shaped by radiative feedback

Nature volume 549, pages 488491 (28 September 2017) | Download Citation

Abstract

The majority of the accreting supermassive black holes in the Universe are obscured by large columns of gas and dust1,2,3. The location and evolution of this obscuring material have been the subject of intense research in the past decades4,5, and are still debated. A decrease in the covering factor of the circumnuclear material with increasing accretion rates has been found by studies across the electromagnetic spectrum1,6,7,8. The origin of this trend may be driven by the increase in the inner radius of the obscuring material with incident luminosity, which arises from the sublimation of dust9; by the gravitational potential of the black hole10; by radiative feedback11,12,13,14; or by the interplay between outflows and inflows15. However, the lack of a large, unbiased and complete sample of accreting black holes, with reliable information on gas column density, luminosity and mass, has left the main physical mechanism that regulates obscuration unclear. Here we report a systematic multi-wavelength survey of hard-X-ray-selected black holes that reveals that radiative feedback on dusty gas is the main physical mechanism that regulates the distribution of the circumnuclear material. Our results imply that the bulk of the obscuring dust and gas is located within a few to tens of parsecs of the accreting supermassive black hole (within the sphere of influence of the black hole), and that it can be swept away even at low radiative output rates. The main physical driver of the differences between obscured and unobscured accreting black holes is therefore their mass-normalized accretion rate.

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Acknowledgements

This work is dedicated to the memory of our friend and collaborator Neil Gehrels. We acknowledge the work done by the Swift/BAT team to make this project possible. We thank M. Kishimoto, C.-S. Chang, D. Asmus, M. Stalevski, P. Gandhi and G. Privon for discussions. We thank N. Secrest for providing us with the stellar masses of the Swift/BAT sample. This paper is part of the Swift/BAT AGN Spectroscopic Survey (BASS, http://www.bass-survey.com). This work is sponsored by the Chinese Academy of Sciences (CAS), through a grant to the CAS South America Center for Astronomy (CASSACA) in Santiago, Chile. We acknowledge financial support from FONDECYT 1141218 (C.R., F.E.B.), FONDECYT 1160999 (E.T.), Basal-CATA PFB–06/2007 (C.R., E.T., F.E.B.), the China-CONICYT fund (C.R.), the Swiss National Science Foundation (grant PP00P2 138979 and PP00P2 166159, K.S.), the Swiss National Science Foundation (SNSF) through the Ambizione fellowship grant PZ00P2 154799/1 (M.J.K.), the NASA ADAP award NNH16CT03C (M.J.K.), the Chinese Academy of Science grant no. XDB09030102 (L.C.H.), the National Natural Science Foundation of China grant no. 11473002 (L.C.H.), the Ministry of Science and Technology of China grant no. 2016YFA0400702 (L.C.H.), the ERC Advanced Grant Feedback 340442 (A.C.F.), and the Ministry of Economy, Development, and Tourism’s Millennium Science Initiative through grant IC120009, awarded to The Millennium Institute of Astrophysics, MAS (F.E.B.). Part of this work was carried out while C.R. was Fellow of the Japan Society for the Promotion of Science (JSPS) at Kyoto University. This work was partly supported by the Grant-in-Aid for Scientific Research 17K05384 (Y.U.) from the Ministry of Education, Culture, Sports, Science and Technology of Japan (MEXT). We acknowledge the usage of the HyperLeda database (http://leda.univ-lyon1.fr).

Author information

Affiliations

  1. Instituto de Astrofísica, Facultad de Física, Pontificia Universidad Católica de Chile, Casilla 306, Santiago 22, Chile

    • Claudio Ricci
    • , Ezequiel Treister
    •  & Franz E. Bauer
  2. Chinese Academy of Sciences South America Center for Astronomy and China-Chile Joint Center for Astronomy, Camino El Observatorio 1515, Las Condes, Santiago, Chile

    • Claudio Ricci
  3. Kavli Institute for Astronomy and Astrophysics, Peking University, Beijing 100871, China

    • Claudio Ricci
    • , Luis C. Ho
    •  & Yanxia Xie
  4. Institute for Astronomy, Department of Physics, ETH Zurich, Wolfgang-Pauli-Strasse 27, CH-8093 Zurich, Switzerland

    • Benny Trakhtenbrot
    • , Michael J. Koss
    • , Kevin Schawinski
    • , Kyuseok Oh
    • , Isabella Lamperti
    •  & Anna Weigel
  5. Eureka Scientific Inc., 2452 Delmer Street Suite 100, Oakland, California 94602, USA

    • Michael J. Koss
  6. Department of Astronomy, Kyoto University, Kyoto 606-8502, Japan

    • Yoshihiro Ueda
  7. Department of Astronomy and Joint Space-Science Institute, University of Maryland, College Park, Maryland 20742, USA

    • Richard Mushotzky
  8. Department of Astronomy, School of Physics, Peking University, Beijing 100871, China

    • Luis C. Ho
    •  & Yanxia Xie
  9. Space Science Institute, 4750 Walnut Street, Suite 205, Boulder, Colorado 80301, USA

    • Franz E. Bauer
  10. Millenium Institute of Astrophysics, Santiago, Chile

    • Franz E. Bauer
  11. Department of Astronomy, University of Geneva, chemin d’Ecogia 16, CH-1290 Versoix, Switzerland

    • Stephane Paltani
  12. Institute of Astronomy, Madingley Road, Cambridge CB3 0HA, UK

    • Andrew C. Fabian
  13. NASA Goddard Space Flight Center, Greenbelt, Maryland 20771, USA

    • Neil Gehrels

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Contributions

C.R. wrote the manuscript with comments and input from all authors, and performed the analysis. B.T. calculated the bolometric corrections, B.T., M.J.K., K.O. and I.L. analysed the optical spectra and inferred the black hole masses, C.R. carried out the broad-band X-ray spectral analysis and Y.U. calculated the intrinsic column density distribution of AGN for different ranges of the Eddington ratio.

Competing interests

The authors declare no competing financial interests.

Corresponding author

Correspondence to Claudio Ricci.

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